Leader block for magnetic tape cartridge

ABSTRACT

The improved leader block uses a substantially rectangular body that is equipped with two tape guide projections which form, in conjunction with the front of the body, a U-shaped channel open at one end and adapted to received the end of the magnetic tape that extends through the opening in the housing of the magnetic tape cartridge. The size and shape of this U-shaped channel substantially corresponds to the dimensions of the magnetic tape in order to precisely align the magnetic tape within the channel and with reference to the leader block body. The section of the front of the leader block body that constitutes the bottom of the U-shaped channel includes a plurality of parallel oriented, spaced apart grooves inscribed therein. These grooves extend from the top tape guide projection to the bottom tape guide projection in order to provide slots to receive corresponding projections that are included on the surface of the cover of the leader block. The cover fits into the U-shaped channel once the magnetic tape has been placed therein to sandwich the magnetic tape between the cover and the body of the leader block. The projections on the cover force the magnetic tape into the corresponding grooves in the face of the leader block body in order to thereby prevent the movement of the end of the magnetic tape with reference to the body of the leader block.

FIELD OF THE INVENTION

This invention relates to magnetic tape cartridges and, in particular,to an improved leader block that is attached to one end of the magnetictape contained in the magnetic tape cartridge and which is used toextract the tape from the cartridge.

PROBLEM

It is a problem in the field of 3480-type magnetic tape cartridges toprovide a leader block that securely and precisely fastens to one end ofthe magnetic tape contained in the magnetic tape cartridge while alsobeing simple to install on the magnetic tape without the use ofcomplicated tools. A misalignment of the magnetic tape to the leaderblock can result in the cartridge and the leader block becoming jammedin the tape drive. Existing leader blocks in use on 3480-type magnetictape cartridges require the use of special installation tools to attainthe required alignment between the magnetic tape and the leader blockwhich makes field installation of leader blocks on the 3480-typemagnetic tape cartridges a difficult task.

These existing leader blocks are oriented such that the magnetic tapeexits the leader block from the side. The side exit of the tape from theleader block places a strain on the magnetic tape and can interfere withthe fit between the leader block and the takeup reel. When the leaderblock is fully inserted into the takeup reel, the leader block forms apart of the outer circumference of the takeup reel and thus the magnetictape winding surface. Any misalignment of the magnetic tape to theleader block or a failure to properly seat the leader block in thetakeup reel results in a non-uniform tape winding surface which causesundesirable impressions in the magnetic tape as it is wrapped on thetakeup reel. Finally, special leader block docking mechanisms must beemployed in order to smoothly seat the leader block in the magnetic tapecartridge.

While this existing leader block apparatus is fairly reliable in itsoperation, the above noted limitations represent detrimental designlimitations contained therein.

SOLUTION

The above described problems are solved and a technical advance achievedin the field by the improved leader block for magnetic tape cartridgesof the present invention. This leader block is simple to install withoutthe use of complex installation tools to thereby enable field personnelto affix a leader block to a magnetic tape cartridge. This leader blockalso orients the magnetic tape to exit the leader block through one endthereof in order to minimize the strain on the magnetic tape and toavoid undesirable impressions on the magnetic tape as it is wrapped onthe takeup reel.

This is accomplished by the use of a substantially rectangular body thatis preferably equipped with two tape guide projections which form, inconjunction with the front of the body, a U-shaped channel open at oneend and adapted to receive the end of the magnetic tape that extendsthrough the opening in the housing of the magnetic tape cartridge. Thesize and shape of this U-shaped channel substantially corresponds to thedimensions of the magnetic tape in order to precisely align the magnetictape within the channel and with reference to the leader block body. Thesection of the front of the leader block body that constitutes thebottom of the U-shaped channel preferably includes either one or aplurality of parallel oriented, spaced apart grooves inscribed therein.These grooves extend from the top tape guide projection to the bottomtape guide projection and receive corresponding projections on thesurface of the cover of the leader block. The cover preferably fits intothe U-shaped channel once the magnetic tape has been placed therein tosandwich the magnetic tape between the cover and the body of the leaderblock. The projections on the cover force the magnetic tape into thecorresponding grooves in the face of the leader block body in order tothereby prevent the movement of the end of the magnetic tape withreference to the body of the leader block. The magnetic tape exits thecenterline of the leader block to enable the tape threading arm to pullthe leader block in a straight line with the magnetic tape rather thanat an angle as with existing side exit leader blocks. The centerlinetape exit also allows the leader block to clear a narrow tape threadingpath in the tape drive.

A preferred embodiment of the leader block uses a pin and socketarrangement to pivotally interconnect one end of the cover to the bodyof the leader block in a position to enable the cover to close into theU-shaped channel. The cover in the preferred embodiment is snap fit intothis channel by means of at least one notch placed on the top and bottomtape guide projections. These notches mate with corresponding tabs onthe cover in order to enable the cover to snap fit securely to the bodyof the leader block.

The end of the leader block body opposite the open end of the channelincludes a socket adapted to receive the tape threading arm leader blockpin in order to enable the tape threading arm to grasp the leader blocksecurely and extract the magnetic tape from the magnetic tape cartridge.A notch is also optionally provided on the back of the leader block bodyto engage a leader block latch mechanism contained in the magnetic tapecartridge. Finally, a pair of docking pins are preferably included onthe top and bottom of the body of the leader block, juxtaposed to themagnetic tape threading end, in order to guide the leader block into theopening in the magnetic tape cartridge when the magnetic tape is rewoundon the magnetic tape cartridge reel. The docking pins also guide theleader block into the takeup reel during the magnetic tape threadingoperation. This architecture provides a leader block that can beassembled without the use of fasteners or special tools in a fieldenvironment. This leader block simply aligns and reliably secures themagnetic tape in the leader block.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 illustrates an exploded perspective view of the leader block ofthe present invention;

FIG. 2 illustrates an end perspective view of the assembled leaderblock;

FIG. 3 illustrates a perspective view of the magnetic tape cartridge;and

FIGS. 4 and 5 illustrate a leader block latch mechanism container in themagnetic tape cartridge.

DETAILED DESCRIPTION

One type of computer system tape transport presently in use makes use ofthe IBM 3480-type magnetic tape cartridge as the data storage media. The3480-type magnetic tape cartridge consists of a substantiallyrectangular exterior housing that contains a single reel of magnetictape with a leader block affixed to one end of the magnetic tape. Theleader block is exposed through an opening in the exterior housing ofthe magnetic tape cartridge for use by an associated tape drive toretrieve the magnetic tape from the magnetic tape cartridge. A tapethreading arm in the tape drive grasps the leader block to extract themagnetic tape through the opening in the one corner of the magnetic tapecartridge and transport the leader block along a tape threading path tobe inserted into the takeup reel of the tape drive.

The external dimensions and architecture of the 3480-type magnetic tapecartridge are an industry standard, as is the tape threading arm leaderblock pin that is used to grasp the leader block. The leader blockillustrated in FIGS. 1 and 2 interfaces to equivalent elements anddetails of the magnetic tape cartridge and tape threading arm leaderblock pin are omitted for the sake of brevity.

Leader Block Body

FIG. 1 illustrates an exploded perspective view of the leader block 100of the present invention and FIG. 2 illustrates an end perspective viewof leader block 100 in its assembled form. Leader block 100 consists ofa body 101 and a cover 102 which function, when interconnected asillustrated in FIG. 2, to sandwich magnetic tape 103 therebetween inorder to securely and precisely fasten leader block 100 to magnetic tape103. It is critical to the reliable operation of the magnetic tapecartridge 300 (FIG. 3) to have leader block 100 precisely oriented withrespect to magnetic tape 103 and securely fastened thereto. Therefore,leader block 100 must be self aligning with reference to magnetic tape103 as well as securely fastened thereto. This is accomplished withoutthe use of fasteners or the need for a special assembly mechanism bymeans of the simple snap fit, self aligning design of leader block 100.

Magnetic tape 103 has a first end 104 which extends through the opening301 in the magnetic tape cartridge 300 to enable the associated tapedrive to extract magnetic tape 103 from the magnetic tape cartridge 300by means of leader block 100 which is attached to magnetic tape 103 atfirst end 104. Leader block 100 includes body 101 that has a top 111, abottom 112, a front 113, a back 114, a first side 115 and a second side116. The top 111 and bottom 112 of body 101 include a first tape guideprojection 121 and a second tape guide projection 122, respectively,which are extensions of top 111 and bottom 112 that protrude over thefront 113 of body 101. First tape guide projection 121, front 113 andsecond tape guide projection 122 in combination form a substantiallyU-shaped channel open at one end and adapted to receive the first end104 of magnetic tape 103. The dimensions of the first tape guideprojection 121 and the second tape guide projection 122 are such thatthe U-shaped channel formed therebetween substantially matches thephysical dimensions of the first end 104 of magnetic tape 103. Magnetictape 103 exits first side 115 of leader block 100 substantially at thecenterline C--C of first side 115. This allows the tape threading arm topull leader block 100 in a straight line with magnetic tape 103. Thestraight line pull of leader block 100 also provides a narrow crosssection profile to the tape threading path and permits the use of anarrower tape threading path than presently used.

Leader Block Assembly

In the assembly of leader block 100, a craftsperson places first end 104of magnetic tape 103 in the bottom of U-shaped channel (described above)coplanar with and juxtaposed to front 113 of body 101. The U-shapedchannel precisely aligns body 101 with the long dimension of magnetictape 103 such that the top and bottom edges of magnetic tape 103 areparallel to top 111 and bottom 112 of leader block 100. A plurality ofparallel oriented spaced apart grooves 131-133 are inscribed in thefront 113 of body 101 in the bottom of the U-shaped channel. Thesegrooves 131-133 illustrated in FIG. 1 are shown as rectangular shapedchannels although their number (at least one), precise geometry anddimensions are a matter of engineering choice and alternatively can beV-shaped grooves or semi-cylindrical troughs. These plurality of grooves131-133 extend substantially along the full width of the U-shapedchannel from first tape guide projection 121 to second tape guideprojection 122. Cover 102 of leader block 100 includes a like pluralityof parallel oriented spaced apart projections 151-153 that mate withgrooves 131-133. Thus, when cover 102 and body 101 are interconnected asillustrated in FIG. 2, the projections 151-153 force sections ofmagnetic tape 103 into the corresponding grooves 131-133 to form a lockmechanism to securely fix first end 104 of magnetic tape 103 withinleader block 100. The use of the rectangular shaped grooves 131 133 andtriangular projections 151-153 cause magnetic tape 103 to be rigidlyconnected to leader block 100.

Leader Block Cover

The interconnection of cover 102 and body 101 in the preferredembodiment is accomplished by means of both tab and notch as well as pinand socket mechanisms. These two mechanisms are illustrative of a simpleway to snap fit body 101 and cover 102 together, although there areother mechanical interconnections that are alternatives to thoseillustrated herein. Cover 102 includes a pin 155 located at a first end143 thereof, which pin 155 is insertable into socket 125 locatedproximate to the second side 116 of body 101. The pin 155 of cover 102is snapped into socket 125 thereby enabling cover 102 to hingeably pivotabout the pin and socket joint to simplify the mechanicalinterconnection of cover 102 and body 101. Once cover 102 is hingeablyconnected to body 101, the opening between front 113 of body 101 andback 142 of cover 102 at the first side 115 of body 101 constitutes anaperture located at the centerline of leader block 100 and adapted toreceive first end 104 of magnetic tape 103. The size of this aperture isa function of the position of cover 102 and the second end 144 of cover102 can be closed to come into contact with body 101 such that backsurface 142 of cover 102 sandwiches first end 104 of magnetic tape 103to front 113 of body 101. The locking of cover 102 to body 101 iscompleted by the use of tabs 154, 156 located on the top and bottom ofcover 102, which tabs interconnect with notches 123 and 124 located onfirst tape guide projection 121 and second tape guide projection 122,respectively. As illustrated in FIG. 1, tabs 154, 156 are triangularshaped elements while notches 123 and 124 are V-shaped grooves adaptedto receive tabs 154, 156. The exact geometry of tabs 154, 156 andnotches 123, 124 are illustrative and not intended to limit theapplicability of the concept illustrated herein. The notches 123, 124extend lengthwise along a section of first tape guide projection 121 andsecond tape guide projection 122, and the exact length of tabs 154, 156on cover 102 is a matter of design choice and must be sufficient tosecurely interlock cover 102 with body 101.

Additional Leader Block Features

Leader block 100 also includes a tape threading arm socket 128 locatedat the second side 116 thereof, which tape threading arm socket 128 isadapted to receive a tape threading arm pin. The tape threading armsocket 128 comprises a substantially semi-cylindrical socket extendingfrom the top 111 of body 101 a significant portion of the way towardsbottom 112 of body 101.

Also included in leader block 100 is a pair of substantially cylindricaldocking pins 126, 127 which function to align leader block 100 with theopening 301 in the magnetic tape cartridge 300 (FIG. 3). Docking pins126, 127 are located on the top 111 and bottom 112 of body 101 andlocated proximate to the first side 115 thereof. As the magnetic tape103 is withdrawn into the magnetic tape cartridge 300, the first side115 of leader block 100 reaches the opening 301 in the magnetic tapecartridge 300, causing docking pins 126, 127 encounter the edges ofguide slots 302 to guide the first side 115 of leader block 100 intothis opening 301 in order to enable leader block 100 to seat in theopening 301 in the magnetic tape cartridge 300. Guide slots 302 aretypically located on the inside surfaces of both the top and bottomsides of magnetic tape cartridge 300. Guide slots 302 are of a shape andextent to precisely define a leader block docking path into opening 301.The use of guide slots 302 enable the leader block 100 to be preciselypositioned in opening 301 by the tape rewind operation. A similar set ofguide slots may be optionally provided in the takeup reel to perform asimilar leader block guide function and to precisely regulate thepositioning of first end 115 of leader block 100 with respect to thetape winding surface of the takeup reel.

Second end 144 of cover 102 is recessed approximately the thickness ofmagnetic tape 103 from first side 115 of body 101. When the leader block100 is inserted into the takeup reel of the tape drive, the first side115 (which may be curved in shape) of leader block 100 forms a part ofthe outer circumference of the takeup reel and thus first side 115 ispart of the magnetic tape winding surface. Docking pins 126, 127precisely determine the location of first side 115 in the takeup reel bymating with corresponding notches in the takeup reel. The magnetic tape103 is wrapped first over second end 144 of cover 102 and thence aroundthe takeup reel. When one complete wrap of tape is taken, first side 115and second end 144 of cover 102 (with one thickness of magnetic tape 103wrapped over second end 144) form a smooth surface to prevent subsequentwraps of magnetic tape 103 on the takeup reel from having impressionsthereon caused by the leader block protruding from the takeup reel.

Leader Block Latch Mechanism

A groove 117 is provided in back 114 of leader block 100 to accept aleader block latch mechanism. Groove 117 can be a rectangular,semi-cylindrical or V-shaped notch extending from top 111 to bottom 112of back 114 of body 101. FIGS. 4 and 5 illustrate a preferred leaderblock latch mechanism that can be incorporated in magnetic tapecartridge 300 to lock leader block 100 into magnetic tape cartridge 300.The leader block latch mechanism 402 consists of a latch arm 403 that ispivotally connected at one end 405 to the housing 417 of the magnetictape cartridge 300 by an appropriate pivot mechanism 406a, 406b, 411includes a socket The pivot mechanism 406a, 406b, 411 includes a socketconsisting of pivot pin cradle 106b and a support 406a to securely affixthis mechanism to the magnetic tape cartridge housing 417 as well asprecisely position it therein. A pivot pin 411 is included in the oneend 405 of latch arm 403 and rests in the socket with one end beingplaced in pivot pin cradle 406b and a second end placed into an openingin support 406a. This pivot arrangement enables latch arm 403 to rotatein direction R as shown in FIG. 5.

Attached to latch arm 403 is a spring 413 that interconnects the latcharm 403 of the latch mechanism 402 to a stop 418 attached to the housing417. Spring 413 is shown as a flexible member attached to latch arm 403in a "living hinge" configuration to place the latch arm 402 in a firstposition (FIG. 4) as a result of the application of a force to the latcharm 403 by the spring 413. This first position is the leader blocklocked position illustrated in FIG. 4. In this position, the latch arm403 is located to prevent the withdrawal of the leader block 100 fromthe magnetic tape cartridge housing 417. This is accomplished by the useof a projection 407 at the end of the latch arm 403 that engages acorresponding feature 117 on the leader block 100. If the user or a tapedrive were to attempt to withdraw the leader block 100 from the magnetictape cartridge 300, the forward motion (direction A) of the leader block100 would be arrested by the latch arm 403 encountering the leader blocknotch groove, thereby preventing any motion of the leader block 100 indirection A. Therefore, the leader block 100 is captured between thelatch arm 103 and the docking stop wherein the leader block groove 117prevents the leader block 100 from moving in either of its normaloperational directions (+A, -A). Spring 413 maintains latch arm 403 inthis locked position absent the application of any exterior force inorder to always provide a leader block lock function to safeguard theintegrity of the magnetic tape 103 contained within the magnetic tapecartridge 300.

Release of Leader Block Latch Mechanism

The latch mechanism 402 is shifted to its second position, illustratedin FIG. 5, by the application of an external force to latch arm 403 toovercome the force applied thereon by the spring 413. This force isgenerally applied thereon by the spring 413. This force is generallyapplied to latch arm 403 through the insertion of a leader block latchrelease pin 412 through an aperture 414 in the bottom of the magnetictape cartridge housing 417 to rotate the latch arm 403 in a verticaldirection (R) about pivot pin 411, such that the end 404 of the latcharm 403 clears the leader block groove 117 on the leader block 100 toenable a user or a tape drive to extract the leader block 100 fromwithin the magnetic tape cartridge housing 417.

This latch release pin 412 is typically part of the tape drive mechanismand is positioned adjacent to the drive hub on which the magnetic tapecartridge 300 is placed by the tape drive mechanism. Therefore, as themagnetic tape cartridge 300 is loaded onto the drive hub by the user orby an appropriate elevator mechanism contained within the tape drive, asis well known in the art, the latch release pin 412 contained in thistape drive mechanism enters aperture 414 in the bottom of the magnetictape cartridge housing 417 and encounters latch arm 403 which is lockingthe leader block 100 in its locked position. As the magnetic tapecartridge 300 is lowered further on the drive hub, this latch releasepin 412 forces the latch arm 403 to rotate about pivot pin 411 in avertical direction a sufficient distance to enable the projection 407 onthe end 404 of the latch arm 403 to clear the leader block groove 117contained on the leader block 100 thereby freeing the leader block 100to be withdrawn from the magnetic tape cartridge housing 417.

SUMMARY

As can be seen from the assembled structure of FIG. 2, magnetic tape 103exits leader block 100 via first side 115 at a point substantially inthe middle (centerline) of first side 115. Leader block 100 exerts alinear force on magnetic tape 103 in a direction that is coplanar withthe surface of magnetic tape 103 thereby avoiding any tangential oracute angle components of this force which have a tendency to causemagnetic tape 103 to tear. The simple snap fit architecture of leaderblock 100 enables a craftsperson to quickly assembly leader block 100and interconnect it to the magnetic tape 103 without the use offasteners or special tools while precisely aligning magnetic tape 103with leader block 100.

While a specific embodiment of this invention has been disclosed, it isexpected that those skilled in the art can and will design alternateembodiments, of this invention that fall within the scope of theappended claims.

We claim:
 1. A leader block for a magnetic tape having a first end,comprising:a substantially rectangular body means having top, bottom,front, back, first and second sides thereto, wherein said top and bottominclude first and second tape guide projections, respectively, extendingoutward from said front, coplanar with said top and bottom sides,respectively, to form with said front a substantially U-shaped channel,open at one end to said first side, to receive said first end of saidmagnetic tape and align said first end of said magnetic tape coplanarwith said front and juxtaposed thereto; and cover means latchablyinsertable into said substantially U-shaped channel of said body meansto sandwich said first end of said magnetic tape between said covermeans and said front of said body means to secure said first end of saidmagnetic tape in said U-shaped channel of said body means.
 2. The leaderblock of claim 1 wherein said first and second tape guide projectionseach include at least one notch for mating with corresponding tabs onsaid cover means to fasten said cover means and said body meanstogether.
 3. The leader block of claim 2 wherein said cover means andsaid body means snap fit together via said notches and correspondingtabs.
 4. The leader block of claim 2 wherein said notches aresubstantially V-shaped grooves and said tabs are substantially V-shapedprojections.
 5. The leader block of claim 1 wherein said cover meansincludes a pin located at a first end of said cover means, which saidfirst end is proximate said second side of said body means for matingwith a corresponding socket located on said front of said body means,proximate said second side of said body means.
 6. The leader block ofclaim 1 wherein said front of said body means includes at least onegroove inscribed in said front, extending substantially from said firsttape guide projection to said second tape guide projection and adaptedto receive a mating projection, located on a surface of said cover meansfacing said front of said body means, to insert said first end of saidmagnetic tape into said groove when said cover means is fastened to saidbody means.
 7. The leader block of claim 6 wherein said at least onegroove is substantially rectangular in cross section and said matingprojection is substantially V-shaped.
 8. The leader block of claim 1wherein said front of said body means includes a plurality of parallelspaced apart grooves inscribed in said front, extending substantiallyfrom said first tape guide projection to said second tape guideprojection and adapted to receive a mating like plurality of parallelspaced apart projections, located on a surface of said cover meansfacing said front of said body means, to insert said first end of saidmagnetic tape into said plurality of grooves when said cover means isfastened to said body means.
 9. The leader block of claim 8 wherein saidplurality of parallel spaced apart grooves are each substantiallyrectangular in cross section and said mating projections aresubstantially V-shaped.
 10. The leader block of claim 1 wherein saidsecond end of said body means includes a substantially semi-cylindricalnotch adapted to receive a tape threading mechanism leader blockthreading pin.
 11. The leader block of claim 1 further including firstand second docking pin means located on said top and bottom,respectively of said body means, proximate said first side and adaptedto guide said leader block into an opening in a magnetic tape cartridgethat houses said magnetic tape.
 12. The leader block of claim 11,wherein said magnetic tape in enclosed within a magnetic tape cartridgehaving a leader block latch mechanism including a latch member toprevent the withdrawal of said leader block from said magnetic tapecartridge, said docking pin means being located on said leader block toengage said latch member.
 13. The leader block of claim 11 wherein saidfirst and second docking pin means are substantially cylindrical inshape.
 14. The leader block of claim 1, wherein said magnetic tape inenclosed within a magnetic tape cartridge having a leader block latchmechanism including a latch member to prevent the withdrawal of saidleader block from said magnetic tape cartridge, said leader blockfurther comprising:means adapted to receive said latch member when saidleader block is withdrawn into said magnetic tape cartridge.
 15. Theleader block of claim 14 wherein said receiving means comprises a grooveon said leader block adapted to engage a corresponding mating feature onsaid latch member.
 16. The leader block of claim 13 wherein saidreceiving means comprises a notch extending substantially across saidback of said leader block from said top to said bottom of said leaderblock and of a geometry to receive a mating projection on said latchmember.
 17. A leader block for a magnetic tape having a first end,comprising:a substantially rectangular body means having top, bottom,front, back, first and second sides thereto, wherein said top and bottominclude first and second tape guide projections, respectively, extendingoutward from said front, coplanar with said top and bottom, respectivelyto form with said front a substantially U-shaped channel, open at oneend to said first side, to receive said first end of said magnetic tapeand align said first end of said magnetic tape coplanar with said frontand juxtaposed thereto; and cover means insertable into saidsubstantially U-shaped channel of said body means wherein said front ofsaid body means includes at least one groove inscribed in said front,extending substantially from said first tape guide projection to saidsecond tape guide projection and adapted to receive a mating projection,located on a surface of said cover means facing said front of said bodymeans, to insert said first end of said magnetic tape into said groovewhen said cover means is fastened to said body means to sandwich saidfirst end of said magnetic tape between said cover means and said frontside of said body means in a manner to prevent movement of said firstend of said magnetic tape with reference to said body means, whereinsaid first and second tape guide projections each include at least onenotch for mating with corresponding tabs on said cover means to fastensaid cover means and said body means together.
 18. The leader block ofclaim 17 wherein said cover means and said body means snap fit togethervia said notches and corresponding tabs.
 19. The leader block of claim17 wherein said notches are substantially V-shaped grooves and said tabsare substantially V-shaped projections.
 20. The leader block of claim 17wherein said cover means includes a pin located at a first end of saidcover means, which said first end is proximate said second side of saidbody means for mating with a corresponding socket located on said frontof said body means, proximate said second side of said body means. 21.The leader block of claim 17 wherein said second end of said body meansincludes a substantially semi-cylindrical notch adapted to receive atape threading mechanism leader block threading pin.
 22. The leaderblock of claim 17 further including first and second substantiallycylindrical docking pin means located on said top and bottom,respectively of said body means, proximate said first side and adaptedto guide said leader block into an opening in a magnetic tape cartridgethat houses said magnetic tape.
 23. The leader block of claim 22,wherein said magnetic tape in enclosed within a magnetic tape cartridgehaving a leader block latch mechanism including a latch member toprevent the withdrawal of said leader block from said magnetic tapecartridge, said docking pin means being located on said leader block toengage said latch member.
 24. The leader block of claim 17 wherein saidat least one groove is substantially rectangular in cross section andsaid mating projection is substantially V-shaped.
 25. The leader blockof claim 17, wherein said magnetic tape in enclosed within a magnetictape cartridge having a leader block latch mechanism including a latchmember to prevent the withdrawal of said leader block from said magnetictape cartridge, said leader block further comprising:means adapted toreceive said latch member when said leader block is withdrawn into saidmagnetic tape cartridge.
 26. The leader block of claim 25 wherein saidreceiving means comprises a groove on said back of said leader blockadapted to engage a corresponding mating feature on said latch member.27. The leader block of claim 24 wherein said receiving means comprisesa notch extending substantially across said back of said leader blockfrom said top to said bottom of said leader block and of a geometry toreceive a mating projection on said latch member.
 28. A leader block fora magnetic tape having a first end, comprising:a substantiallyrectangular body means having a substantially U-shaped channel, open atone end thereof to receive said first end of said magnetic tape andalign said first end of said magnetic tape coplanar with the bottom ofsaid substantially U-shaped channel and juxtaposed thereto, wherein asecond end of said body means, distal from said first end, includes asubstantially semi-cylindrical notch adapted to receive a tape threadingmechanism leader block threading pin; and cover means latchablyinsertable into said substantially U-shaped channel of said body meansto sandwich said first end of said magnetic tape between said covermeans and said bottom of said substantially U-shape channel to securesaid first end of said magnetic tape in said U-shaped channel of saidbody means.
 29. The leader block of claim 28 wherein the walls of saidsubstantially U-shaped channel each include at least one notch formating with corresponding tabs on said cover means to fasten said covermeans and said body means together.
 30. The leader block of claim 29wherein said cover means and said body means snap fit together via saidnotches and corresponding tabs.
 31. The leader block of claim 29 whereinsaid notches are substantially V-shaped grooves and said tabs aresubstantially V-shaped projections.
 32. The leader block of claim 28wherein said cover means includes a pin located at a first end of saidcover means, which for hingeably mating with a corresponding socketlocated on said body means.
 33. The leader block of claim 28 whereinsaid bottom of said substantially U-shaped channel includes at least onegroove inscribed therein, extending substantially from side to sidealong said bottom and adapted to receive a mating projection located ona surface of said cover means facing said bottom of said substantiallyU-shape channel to insert said first end of said magnetic tape into saidgroove when said cover means is fastened to said body means.
 34. Theleader block of claim 33 wherein said at least one groove issubstantially rectangular in cross section and said mating projection issubstantially V-section shaped.
 35. The leader block of claim 28 whereinsaid bottom of said substantially U-shaped channel includes a pluralityof parallel spaced apart grooves inscribed therein, extendingsubstantially from side to side along said bottom and adapted to receivea mating like plurality of parallel spaced apart projections located ona surface of said cover means facing said bottom of said substantiallyU-shape channel to insert said first end of said magnetic tape into saidgroove when said cover means is fastened to said body means.
 36. Theleader block of claim 35 wherein said plurality of parallel spaced apartgrooves are each substantially rectangular in cross section and saidmating projections are substantially V-shaped.
 37. The leader block ofclaim 28 further including first and second docking pin means located ontop and bottom sides, respectively of said body means and adapted tomate with corresponding docking notches on a magnetic tape cartridgethat houses said magnetic tape.
 38. The leader block of claim 37 whereinsaid first and second docking pin means are substantially cylindrical inshape.
 39. The leader block of claim 37, wherein said magnetic tape inenclosed within a magnetic tape cartridge having a leader block latchmechanism including a latch member to prevent the withdrawal of saidleader block from said magnetic tape cartridge, said docking pin meansbeing located on said leader block to engage said latch member.
 40. Theleader block of claim 28, wherein said magnetic tape in enclosed withina magnetic tape cartridge having a leader block latch mechanismincluding a latch member to prevent the withdrawal of said leader blockfrom said magnetic tape cartridge, said leader block furthercomprising:means adapted to receive said latch member when said leaderblock is withdrawn into said magnetic tape cartridge.
 41. The leaderblock of claim 40, wherein said receiving means comprises a groove onsaid back of said leader block adapted to engage a corresponding matingfeature on said latch member.
 42. The leader block of claim 40 whereinsaid receiving means comprises a notch extending substantially acrosssaid back of said leader block from said top to said bottom of saidleader block and of a geometry to receive a mating projection on saidlatch member.
 43. A substantially rectangular leader block for amagnetic tape having a first end, wherein said leader block has a top, abottom, a front, a back, first and second sides, said leader blockcomprising:means, located substantially along a centerline of saidsecond side, adapted to receive a tape threading mechanism leader blockthreading pin; and an aperture, located substantially along a centerlineof said first side, for receiving said first end of said magnetic tapeto enable said tape threading mechanism leader block threading pin topull said leader block in a straight line with said magnetic tape. 44.The leader block of claim 43, wherein said magnetic tape in enclosedwithin a magnetic tape cartridge having a leader block latch mechanismincluding a latch member to prevent the withdrawal of said leader blockfrom said magnetic tape cartridge, said leader block furthercomprising:means adapted to engage said latch member when said leaderblock is withdrawn into said magnetic tape cartridge.
 45. The leaderblock of claim 44, wherein said engaging means comprises a groove onsaid back of said leader block adapted to engage a corresponding matingfeature on said latch member.
 46. The leader block of claim 44 whereinsaid receiving means comprises a notch extending substantially acrosssaid back of said leader block from said top to said bottom of saidleader block and of a geometry to receive a mating projection on saidlatch member.
 47. The leader block of claim 43 further comprising firstand second docking pin means located on said top and bottom,respectively, of said leader block, proximate said first side andadapted to guide said leader block into an opening in a magnetic tapecartridge that houses said magnetic tape.
 48. The leader block of claim43 wherein said receiving means comprises a substantially cylindricalnotch extending a predetermined distance from said top of said leaderblock along said second side of said leader block toward said bottom ofsaid leader block.